Steve Saunders Goldwing Forums banner

Status
Not open for further replies.
1 - 14 of 14 Posts

·
Premium Member
Joined
·
87 Posts
Discussion Starter #1
imported post

My wife loves to sew and she says she is good at itand since I am middle aged , that means that I am paying to help my parents and my kids and i am in the middle getting milked from both ends.

I bought some wire and connectors we plan to put the wire on the outside of a long sleeve T shirt and sew a sweat shirt over the top of it, can anyone tell me how long the wire should be to get about 70 watts ?

the wire is 30awg silver coated copper 7/38 strand
 

·
Just another ORF!
Joined
·
8,189 Posts
imported post

PM Mike Hirsh.

He was telling me he made his own and he knows how many feet you need to get the warmth you are looking for.
 

·
Banned
Joined
·
12,287 Posts
imported post

...what's the wire ohm-out @ per foot?

I'm guessing you'll need appx. 30'-35' +/- of it at 13.5V for about 45W heat...

Suggestion: ...stay off of elbows and shoulderblades as the heat will feel more intense there. Concentrate around the openings; neck and lower back area.
 

·
Anti-Guru
Joined
·
2,711 Posts
imported post

laydeane wrote:
...can anyone tell me how long the wire should be to get about 70 watts ?

the wire is 30awg silver coated copper 7/38 strand
70W from a 12.8V (assumed) source would require 2.34 ohms of resistance (using R = V^2/P) (alternator output of 13.5V values in this violet color - so 2.6 ohms for 70W @ 13.5V)

The Belden 83043 002100 7/38 in your photo should have a resistance of 103.2 ohms/ 1000-feet.

Math gets you to needing 22-feet 8 & 3/32-inches of your wire to achieve 70W at 12.8 volts. So the direct answer to your question is 22-feet 8 & 3/32-inches (for 13.5V 25-feet 2 & 5/16 inches) Remember that 70W will pull 5.0-Amps (5.2-Amps) from your bike

This puts you at about 3-Watts per foot of wire, so you will wanna be careful to keep bend radii loose to avoid concentrating too much heat in one area. For reference, the 194 light bulb used for marker lamps (and dash bulbs) burns at just over 3-Watts (grab one of those when it's lighted to get a feel for why you'll wanna think about larger radius turns !).

The 33' length offers about 3.41 ohms of resistance for 48-Watts providing 1.45-Watts per foot of wire, which will probably make for fewer hot-spots (53.4-Watts providing 1.62-Watts per foot @ 13.5V ); drawing3.8-Amps (4.0-Amps) from your bike's electrical system.

Yeah, math is all fun; hopefully, you can see how the watt-density of the wires kinda "hop-up" pretty high if you're not careful.


That said, you can control the power in the system to make a 70W (max) liner feel like a soft-heating 30 W liner and still have the extra cooking power to warm you if needd by adding a simple contoller. My personal favorite is the MX033 (about $20) can be had from quite a few places and it's a simple in-line componant (here's a link to one of many sources). The nice thing on this controller is that it'll handle up to about 15 A of load, so it's much less prone to failure than some of the commercially available 'heated gear' controlles that were all familiar with, and it doesn't waste power by dissipating heat (as a resistive controller will do)...


One comment on the Belden 83043 002100 -- that spool is NOT spec'd to be one continous length... Sometimes there will be several shorter lengths on that spool, though I believe Belden has a minimum length of 25' if there are separate lengths loaded onto the spool...

Not that I've thought about this at all or anything... ;) (does anyone read all this?)
 

·
Anti-Guru
Joined
·
2,711 Posts
imported post

Sorry, one quick add'l thought -- a "cording foot" for the sewing machine can make all 22-33 feet of 30-AWG wire fly-by in seconds using Zig-Zag stitching...
http://www.singerco.com/uploads/assets/pdf/CordingSewingMC.pdf

The foot I have for the "shop machine" (Singer 403A) will feed 30AWG directly to the stitch -- the wire is centered into the stich pattern, and you can sew using a common Zig-Zag pattern (similar to a piping foot, but the feed-path on the cording foot is more robust and some of the piping feet won't allow for Zig-Zag...)
 

·
Premium Member
Joined
·
2,523 Posts
imported post

Nice find in the controller Satan. I have a fleece jacket I always wanted to turn into a heated jacket liner. I was just never sure about what controller to use.
 

·
Banned
Joined
·
12,287 Posts
imported post

Here is a switch option.
 

·
Premium Member
Joined
·
87 Posts
Discussion Starter #12
imported post

yes Satan I Have read all of it three times now and I will keep reading it becouse it is amazing to me that you understand it so well. It makes me feel dirt dumb when I see some one with your knowledge and I thank you for sharing.

I would greatly appreciate any advice on our project , we were going to do his and hers jacket liners first and pants and gloves later.

I will be ordering two of the controllers you talked about and some more wire.

My Questions now are is this the best wire to use and should i use the same length in the pants as in the jackets?

Thank You
 

·
Anti-Guru
Joined
·
2,711 Posts
imported post

PTFE insulation is ultra thin which helps the flexibility, feel, and the heat transfer & Silver plated Copper 7/38 is good stuff. So you're all good there. I think that this is a good compromise with length required for current draw and the watt densities...

The length is what will ultimately determine the "heat" (kinda like the math above talks about) ... loger wire will run cooler - so I'd think it best to work with fairly similar lengths for the garments.

Trying to keep the heat evenly spaced on the places that you'll want heat is usually more of an issue... Try cutting a length of string to the length of the wire you're planning to work with... and lay out a pattern on what you're gonna use (your spouse may be familiar with markers that'll wash out so that patterns can be written right onto the fabric and cleaned off later).

I don't wanna step on any toes here by adding this into this forum/thread, but I prolly have some wire on a spool here that I could sellon a per-foot basis (depending on your need) - nothing as attractive as your red stuff, but it's PTFE 30AWG silver-clad 7/38.

Not mentionted in all the "calculations" above (or on most of the heated clothing sites) is the power lost in the connecting cables... Like if your bike runs 13.5Volts and you run a 3.41-ohm (53-Watt) jacket and you connect using two-feet of two-conductor 20-AWG wire you'll be dropping some power into the hook-up wire. this isn't much, I'm guessing on the lines of 0.4 Volts lost, but since the power thing is a square of the voltage (above) your 53-Watt vest is now limited to 50W or so. Not a lot, but it is worth a few bucks to keep the harness wires on the bike short and thick (within reason) 18 or 16 AWG are good enough for a 2-foot connection - 14AWG for longer.

Really, you can become distracted in over-thinking these things... and we all know that 30 to 35 feet of wire will get warm when plugged into the bike's battery. Shorter wires get hotter, and the controller will reduce the "heat".

Best not to think it to death and just have a fun DIY effort. Think of good ways to secure the thin Jacket wires and the Connector wires to the jacket -- these take a serious beating. My current favorite is a loop of flat shoelace threaded through shrink tubing so that the shoelace can be stitched to something strong in the jacket, the shring tubing shoul hold onto the connector's cable really really well (the marine-grade stuff is good for this, adding a stitch or two to the lace under the shring tubing adds grip)...

You'll have fun with it - Dive in! You know we're all interested in following along...
 

·
Premium Member
Joined
·
87 Posts
Discussion Starter #14
imported post

I just ordered the controllers and the wife says she can handle the sewing

one more step closer to toasty comfort
 
1 - 14 of 14 Posts
Status
Not open for further replies.
Top